organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

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ISSN: 2056-9890

(E,E)-N1,N2-Bis(2,6-di­fluoro­benzyl­­idene)ethane-1,2-di­amine

aDepartment of Chemistry, Faculty of Science, Islamic Azad University, Shahrekord Branch, Box 166, Tehran, Iran, bDepartment of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, Iran, and cSchool of Chemistry, Newcastle University, Newcastle upon Tyne NE1 7RU, England
*Correspondence e-mail: khaledi1974@yahoo.com

(Received 24 October 2011; accepted 25 October 2011; online 29 October 2011)

The asymmetric unit of the title compound, C16H12F4N2, comprises half of the potentially bidentate Schiff base ligand, with an inversion centre located at the mid-point of the central C—C bond. The crystal packing is stabilized by inter­molecular C—H⋯N and ππ inter­actions [centroid–centroid distance = 3.6793 (12) Å and inter­planar spacing = 3.4999 (7) Å].

Related literature

For background to the synthesis and structural variations of Schiff base ligands and their complexes, see: Granovski et al. (1993[Granovski, A. D., Nivorozhkin, A. L. & Minkin, V. I. (1993). Coord. Chem. Rev. 126, 1-69.]); Elmali et al. (2000[Elmali, A., Zeyrek, C. T., Elerman, Y. & Svoboda, I. (2000). Acta Cryst. C56, 1302-1304.]).

[Scheme 1]

Experimental

Crystal data
  • C16H12F4N2

  • Mr = 308.28

  • Monoclinic, P 21 /n

  • a = 7.3304 (10) Å

  • b = 10.5414 (15) Å

  • c = 9.2106 (13) Å

  • β = 105.487 (2)°

  • V = 685.89 (17) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 0.13 mm−1

  • T = 150 K

  • 0.34 × 0.30 × 0.10 mm

Data collection
  • Bruker SMART 1K CCD area-detector diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2005[Bruker (2005). SADABS, SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.958, Tmax = 0.987

  • 4573 measured reflections

  • 1203 independent reflections

  • 1057 reflections with I > 2σ(I)

  • Rint = 0.031

Refinement
  • R[F2 > 2σ(F2)] = 0.043

  • wR(F2) = 0.124

  • S = 1.15

  • 1203 reflections

  • 100 parameters

  • H-atom parameters constrained

  • Δρmax = 0.27 e Å−3

  • Δρmin = −0.23 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
C5—H5⋯N1i 0.95 2.53 3.471 (2) 171
Symmetry code: (i) [x-{\script{1\over 2}}, -y+{\script{1\over 2}}, z-{\script{1\over 2}}].

Data collection: SMART (Bruker, 2005[Bruker (2005). SADABS, SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2005[Bruker (2005). SADABS, SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]).

Supporting information


Comment top

Schiff base ligands are among the most prevalent ligands in the field of coordination chemistry. Metal derivatives of Schiff bases have been studied extensively, and NiII and CuII complexes play a major role in both synthetic and structural research (Elmali et al., 2000; Granovski et al., 1993).

The asymmetric unit of the title compound comprises half of the potentially bidentate Schiff base ligand; an inversion centre is located in the middle of the central C—C bond (Fig. 1). Each half of the molecule is essentially planar, the imine segment (C1—N1C2—C3) being rotated only 7.36 (10)° out of the plane of the benzene ring. The two halves are parallel by inversion symmetry, but not coplanar, the CH2CH2 linker unit forming a step between them.

The crystal packing is stabilized by intermolecular C—H···N interactions (see Table 1), which generate sheets parallel to (1 0 -1), and by intermolecular π-π interactions [centroid-centroid distance = 3.6793 (12) Å, interplanar separation = 3.4999 (7) Å, the two planes are strictly parallel by inversion symmetry].

Related literature top

For background to the synthesis and structural variations of Schiff base ligands and their complexes, see: Granovski et al. (1993); Elmali et al. (2000).

Experimental top

The title compound was synthesized by mixing 2,4-difluorobenzaldehyde (4 mmol) and ethylenediamine (2 mmol) in chloroform (20 ml). After stirring for 2 h, the solution was filtered and the resulting yellow solid was crystallized from ethanol, giving single crystals suitable for X-ray diffraction.

Refinement top

All H atoms were positioned geometrically and constrained to ride on the parent atoms, with C—H = 0.95–0.99Å and Uiso(H) = 1.2 Ueq(C).

Computing details top

Data collection: SMART (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT (Bruker, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atomic numbering. Symmetry code for suffix A: -x + 1, -y + 1, -z + 2.
[Figure 2] Fig. 2. The crystal packing, viewed down the a axis, showing linking of molecules through the intermolecular C—H···N hydrogen bonds to form sheets in the (1 0 - 1) plane. The dashed lines represent these intermolecular interactions.
(E,E)-N1,N2-Bis(2,6- difluorobenzylidene)ethane-1,2-diamine top
Crystal data top
C16H12F4N2F(000) = 316
Mr = 308.28Dx = 1.493 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 4055 reflections
a = 7.3304 (10) Åθ = 2.9–28.3°
b = 10.5414 (15) ŵ = 0.13 mm1
c = 9.2106 (13) ÅT = 150 K
β = 105.487 (2)°Plate, yellow
V = 685.89 (17) Å30.34 × 0.30 × 0.10 mm
Z = 2
Data collection top
Bruker SMART 1K CCD area-detector
diffractometer
1203 independent reflections
Radiation source: fine-focus sealed tube1057 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.031
Detector resolution: 8.33 pixels mm-1θmax = 25.0°, θmin = 3.0°
ω scansh = 88
Absorption correction: multi-scan
(SADABS; Bruker, 2005)
k = 1212
Tmin = 0.958, Tmax = 0.987l = 1010
4573 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.043Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.124H-atom parameters constrained
S = 1.15 w = 1/[σ2(Fo2) + (0.0646P)2 + 0.2701P]
where P = (Fo2 + 2Fc2)/3
1203 reflections(Δ/σ)max < 0.001
100 parametersΔρmax = 0.27 e Å3
0 restraintsΔρmin = 0.23 e Å3
Crystal data top
C16H12F4N2V = 685.89 (17) Å3
Mr = 308.28Z = 2
Monoclinic, P21/nMo Kα radiation
a = 7.3304 (10) ŵ = 0.13 mm1
b = 10.5414 (15) ÅT = 150 K
c = 9.2106 (13) Å0.34 × 0.30 × 0.10 mm
β = 105.487 (2)°
Data collection top
Bruker SMART 1K CCD area-detector
diffractometer
1203 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2005)
1057 reflections with I > 2σ(I)
Tmin = 0.958, Tmax = 0.987Rint = 0.031
4573 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0430 restraints
wR(F2) = 0.124H-atom parameters constrained
S = 1.15Δρmax = 0.27 e Å3
1203 reflectionsΔρmin = 0.23 e Å3
100 parameters
Special details top

Experimental. The low-temperature data were collected with the Oxford Cyrosystems Cryostream low-temperature attachment.

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
F10.24616 (17)0.28505 (10)0.59397 (12)0.0409 (4)
F20.29841 (19)0.71120 (10)0.45850 (14)0.0434 (4)
N10.4481 (2)0.46153 (14)0.79618 (16)0.0297 (4)
C10.5503 (3)0.51558 (19)0.9411 (2)0.0334 (5)
H1A0.55900.60880.93170.040*
H1B0.68050.48090.97170.040*
C20.3868 (2)0.53796 (16)0.6894 (2)0.0277 (4)
H20.41230.62560.70870.033*
C30.2783 (2)0.50109 (15)0.53673 (18)0.0244 (4)
C40.2091 (2)0.37948 (16)0.49141 (19)0.0272 (4)
C50.1031 (2)0.35046 (18)0.3480 (2)0.0311 (5)
H50.05940.26640.32250.037*
C60.0615 (3)0.44634 (19)0.2419 (2)0.0332 (5)
H60.01230.42790.14260.040*
C70.1257 (3)0.56853 (19)0.2780 (2)0.0330 (5)
H70.09740.63450.20520.040*
C80.2317 (2)0.59168 (16)0.4228 (2)0.0287 (4)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
F10.0569 (8)0.0217 (6)0.0346 (6)0.0067 (5)0.0046 (5)0.0054 (4)
F20.0677 (8)0.0190 (6)0.0419 (7)0.0003 (5)0.0118 (6)0.0036 (5)
N10.0339 (8)0.0273 (8)0.0247 (8)0.0032 (6)0.0022 (6)0.0038 (6)
C10.0331 (10)0.0355 (10)0.0280 (10)0.0021 (8)0.0020 (8)0.0042 (8)
C20.0331 (9)0.0210 (9)0.0287 (9)0.0031 (7)0.0077 (7)0.0021 (7)
C30.0259 (8)0.0230 (9)0.0248 (9)0.0035 (7)0.0075 (7)0.0012 (7)
C40.0306 (9)0.0228 (9)0.0271 (9)0.0030 (7)0.0059 (7)0.0027 (7)
C50.0312 (9)0.0292 (10)0.0308 (10)0.0017 (7)0.0044 (8)0.0059 (7)
C60.0300 (9)0.0421 (11)0.0251 (9)0.0044 (8)0.0032 (7)0.0014 (8)
C70.0370 (10)0.0349 (10)0.0278 (10)0.0101 (8)0.0098 (8)0.0082 (8)
C80.0357 (10)0.0198 (9)0.0324 (10)0.0042 (7)0.0124 (8)0.0007 (7)
Geometric parameters (Å, º) top
F1—C41.349 (2)C3—C81.392 (2)
F2—C81.360 (2)C3—C41.401 (3)
N1—C21.258 (2)C4—C51.376 (3)
N1—C11.461 (2)C5—C61.382 (3)
C1—C1i1.502 (4)C5—H50.950
C1—H1A0.990C6—C71.381 (3)
C1—H1B0.990C6—H60.950
C2—C31.471 (2)C7—C81.374 (3)
C2—H20.950C7—H70.950
C2—N1—C1116.98 (16)F1—C4—C3118.52 (15)
N1—C1—C1i110.12 (19)C5—C4—C3123.79 (16)
N1—C1—H1A109.6C4—C5—C6118.53 (17)
C1i—C1—H1A109.6C4—C5—H5120.7
N1—C1—H1B109.6C6—C5—H5120.7
C1i—C1—H1B109.6C7—C6—C5120.98 (17)
H1A—C1—H1B108.1C7—C6—H6119.5
N1—C2—C3124.56 (16)C5—C6—H6119.5
N1—C2—H2117.7C8—C7—C6117.89 (18)
C3—C2—H2117.7C8—C7—H7121.1
C8—C3—C4114.00 (15)C6—C7—H7121.1
C8—C3—C2120.03 (15)F2—C8—C7118.23 (17)
C4—C3—C2125.95 (15)F2—C8—C3116.95 (16)
F1—C4—C5117.69 (16)C7—C8—C3124.81 (17)
C2—N1—C1—C1i119.1 (2)C3—C4—C5—C60.1 (3)
C1—N1—C2—C3178.90 (15)C4—C5—C6—C70.4 (3)
N1—C2—C3—C8174.14 (17)C5—C6—C7—C80.1 (3)
N1—C2—C3—C47.6 (3)C6—C7—C8—F2178.75 (15)
C8—C3—C4—F1179.76 (15)C6—C7—C8—C30.6 (3)
C2—C3—C4—F11.4 (3)C4—C3—C8—F2178.50 (14)
C8—C3—C4—C50.5 (3)C2—C3—C8—F23.0 (2)
C2—C3—C4—C5177.93 (16)C4—C3—C8—C70.8 (3)
F1—C4—C5—C6179.17 (15)C2—C3—C8—C7177.67 (16)
Symmetry code: (i) x+1, y+1, z+2.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C5—H5···N1ii0.952.533.471 (2)171
Symmetry code: (ii) x1/2, y+1/2, z1/2.

Experimental details

Crystal data
Chemical formulaC16H12F4N2
Mr308.28
Crystal system, space groupMonoclinic, P21/n
Temperature (K)150
a, b, c (Å)7.3304 (10), 10.5414 (15), 9.2106 (13)
β (°) 105.487 (2)
V3)685.89 (17)
Z2
Radiation typeMo Kα
µ (mm1)0.13
Crystal size (mm)0.34 × 0.30 × 0.10
Data collection
DiffractometerBruker SMART 1K CCD area-detector
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2005)
Tmin, Tmax0.958, 0.987
No. of measured, independent and
observed [I > 2σ(I)] reflections
4573, 1203, 1057
Rint0.031
(sin θ/λ)max1)0.594
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.043, 0.124, 1.15
No. of reflections1203
No. of parameters100
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.27, 0.23

Computer programs: SMART (Bruker, 2005), SAINT (Bruker, 2005), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C5—H5···N1i0.952.533.471 (2)171
Symmetry code: (i) x1/2, y+1/2, z1/2.
 

Acknowledgements

MK thanks the Islamic Azad University, Shahrkord Branch, for support of this work. WC and RWH thank the EPSRC (UK) for equipment funding.

References

First citationBruker (2005). SADABS, SMART and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationElmali, A., Zeyrek, C. T., Elerman, Y. & Svoboda, I. (2000). Acta Cryst. C56, 1302–1304.  Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
First citationGranovski, A. D., Nivorozhkin, A. L. & Minkin, V. I. (1993). Coord. Chem. Rev. 126, 1–69.  Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar
First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals Google Scholar

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ISSN: 2056-9890
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